This invention relates generally to electromechanical drives for facilitating the manual movement and positioning of a trailer after the trailer is uncoupled from a towing vehicle and more particularly to wheeled jacks for supporting trailers at their tongues when they uncoupled from the towing vehicle.
There are a variety of types of mechanisms for aiding the transport of a trailer uncoupled from its towing vehicle. One of the most common is the swivel jack.
Swivel jacks are typically pivotally mounted to the tongues of trailers. These jacks typically have wheels at their bases that support the trailer in place of the hitch of the towing vehicle. The jack provides a third support point that cooperates with the two ground support points provided by the conventional two wheels and axle of a trailer. In their simplest implementations, the jacks provide a third ground wheel so that the trailer can be manually pushed or pulled into a storage station or area. Often these areas require the trailer to be moved over surfaces that offer significant resistance to rotation of the trailer wheels, such as gravel or soft turf. An example of a hand-powered swivel jack is the model no. 372169 marine swivel jack, manufactured by Fulton Performance Products of Mosinee, Wis. www.fultonpreformance.com
In order to make these swivel jacks easier to use, motors are sometimes added to them for the purpose of driving the wheel. An example of this type of adaptation of the swivel jack is found in U.S. Pat. No. 3,861,482 (hereinafter xe2x80x9cthe ""482 patentxe2x80x9d), which illustrates a power-driven swivel jack that is detachable from a trailer tongue. A steering arm attached to the body of the swivel jack in the ""482 patent and allows the user to steer the trailer as it moves under the power of the jack. The steering arm extends transversely from the vertical pivot axis of the jack and is attached to the jack at a point such that the steering force is applied to the jack at the top of the jack and along the vertical pivot axis.
Even with power driven swivel jacks, it""s difficult to steer the trailer by controlling a steering arm. Turning the wheel requires considerable force, particularly if the trailer is heavy and the road conditions are other than smooth and hard. In some jacks, this problem is addressed by making the wheel from a hard plastic with a relatively smooth tread. Although this solution makes the jack easier to steer, it compromises the traction of the wheel to the ground, making the driving of the wheel more difficult. Moreover, in the swivel jack illustrated in the ""482 patent, the steering arm is mounted to the top of the jack, which provides the user with very little if any tactile information about the direction of the wheel as the trailer is steered.
None of these known swivel jacks have satisfactory and efficient steering assemblies and wheel mechanisms for easily moving and steering a trailer over rough terrain like gravel or soft turf. In addition, none of these jacks transmit substantially all of the torque for turning and steering the swivel jack to the wheel fork assembly, making the manual steering of the jack sometimes difficult. For example, the swivel jack of the ""482 patent applies the torque for steering the wheel of the jack at the extreme end of the jack opposite the wheel. Thus, some of the torque is taken up in the torsion of the jack caused by the opposing forces at the ends of the jackxe2x80x94i.e., the torque applied at the top of the jack by the steering arm and frictional resistance to it at the interface between the wheel and the ground. This remoteness of the steering force to the resistance it must overcome gives the user a feel that the steering is not nimble and or sluggish in responding to changes in the magnitude or direction of the force applied to the steering arm.
In accordance with the invention, a trailer swivel jack is provided with a steering assembly for maneuvering the power driven jack in a manner that provides the user with a tactile sense of greater control than previously possible. The steering assembly is detachable from the jack by way of a quick release fastener, which allows the steering mechanism to be safely stored away when not being used. Moreover, the steering mechanism also includes a control switch for operating the motor driving the wheel of the jack. Like the mechanical connection of the steering assembly to the jack, the electrical connection between the jack and the assembly is also of a quick release type. Thus, with the steering assembly removed, the jack cannot be powered, which locks the wheel in place.
Additional features and advantages of the invention will be made apparent from the following detailed description of illustrative embodiments that proceeds with reference to the accompanying Figures.